Visitors to the White House will notice a makeshift sign taped to the door of the James S. Brady Press Briefing Room, entry point for the reportorial corps that regularly covers President Donald Trump and his administration. “Masks Required Beyond This Point,” it reads. “Please wear masks over both your nose and mouth at all times.”

The sign was not put up by the White House. The correspondents had to do it themselves.

Throughout a pandemic that has now landed squarely in the West Wing, Trump officials — who routinely shunned masks — declined to institute thorough safety protocols to protect the White House press corps, according to interviews with reporters who now face the prospect of a rapidly escalating outbreak in their daily workspace.

“The only place on the White House grounds where a mask has been required is the White House press area, and the only people who have routinely violated that rule have been White House staff,” Jonathan Karl, ABC’s chief White House correspondent, said in an interview.

Reporters who traveled with Trump over the past week learned that Hope Hicks, his adviser, had tested positive only after reading press reports Thursday. Many had traveled near Hicks, and had spent time with family and friends in the days since.

On Monday, Kayleigh McEnany, the White House press secretary, said she had tested positive for the virus. Two of her deputies, Chad Gilmartin and Karoline Leavitt, also tested positive.

Last Thursday, McEnany stood maskless at her lectern inside the press room and conducted a briefing with more than a dozen reporters, hours before Trump’s positive test was revealed. Over the weekend, she again briefed reporters on the White House grounds without a mask.

At least three White House correspondents have tested positive for the virus in recent days, including a New York Times reporter, Michael D. Shear. All had recently covered official White House events or traveled on Air Force One. Other reporters with potential exposure are being tested daily or self-quarantining as a precaution.

“I felt safer reporting in North Korea than I currently do reporting at The White House,” a CBS News correspondent, Ben S. Tracy, wrote on Twitter on Monday. “This is just crazy.”

White House officials said Monday that they would provide rapid virus tests to reporters who had traveled with Trump over the past week. But the White House asked that the reporters arrive there at the same time for the tests, a condition that worried some correspondents because of the prospect of a gathering of exposed individuals.

John Roberts, the Fox News correspondent who briefly removed his mask during an on-camera exchange with McEnany at her Thursday briefing, said he was feeling healthy but was considering a virus test in light of the press secretary’s announcement.

“I can’t say that I’m surprised at all,” Roberts said during a Fox News segment Monday, “because whatever infection and mode of transmission that has seized the White House, it has literally gone through that building like a scythe.”

The White House Correspondents’ Association, which negotiates with the administration over access and safety issues, said in a statement that it would continue encouraging its members to work remotely if they did not have pressing business at the White House.

“We wish Kayleigh, the president and everyone else struggling with the virus a swift recovery,” the group said.

But White House reporters are also expected to keep close tabs on a dramatic moment for the nation and for Trump’s presidency — work that is difficult to do from a distance. Members of the press corps also constitute the roving pool that closely tracks Trump’s movements, providing citizens with real-time information about their president.

Zeke Miller of the Associated Press, the president of the correspondents’ association, has encouraged his anxious membership to stay vigilant.

“For seven months, we have been cleareyed about the inherent risks in fulfilling our obligation to keeping the American public informed,” Miller wrote in a memo Friday. “Today those risks are more evident than ever, but our work is only growing more vital.”